While interest in protein intake as an approach to lower/maintain body weight has had recent popular and research attention, little is known about associations, cross-sectional or longitudinal, between intakes of specific amino acids (AA) or protein and body mass index (BMI). The overall goal of this project is to assess, in a cost-effective manner using existing databases, relations in individuals of specific AAs and dietary protein with BMI. We propose to study individual AAs (dietary and urinary, respectively) in relation to BMI using data from the International Study of Macro- and Micro-nutrients and Blood Pressure (INTERMAP), a cross-sectional, cooperative, high-quality 17-sample population study of 4,680 men and women ages 40-59 in four countries (China, Japan, U.K., U.S.). We also propose to study the longitudinal associations of dietary protein (total, vegetable and animal) intake with BMI using data from the Chicago Western Electric (WE) Company Study, a longitudinal investigation involving 2,107 men ages 40-55. Data on BMI and 18 dietary AAs from four 24-hour recalls, including alanine, arginine, aspartic acid, cystine, glutamic acid, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, and valine, and a related compound - mono-sodium glutamate (MSG, from China only), and 18 urinary AAs from one timed 24-hour urine specimen, are available in INTERMAP. Data on protein intake including total, vegetable and animal protein from extensive high-quality two diet history assessments, and sequential BMI measurements for 9 years are available in the WE Study. In addition, other major lifestyle factors and diet/nutrient variables are available in both studies. The proposed study seeks to significantly enhance knowledge on individual AAs, protein and BMI that can contribute to improved nutrition for weight control. The findings from this project can be important for further study of the effects of protein composition on body weight, including research using new techniques (e.g. metabolomics). Overall, this proposed study is a cost-effective approach to dealing with important unanswered questions of public health significance related to obesity. The overall goal of the proposed study is to examine, in a cost-effective manner using existing databases, the association between individuals of specific amino acids and dietary protein with body weight. This project has the potential to improve the current limited knowledge on proteins, amino acids and obesity. It is of great public health and clinical significance as obesity is a major health concern. The findings from this project may lead to new research on obesity prevention. [unreadable] [unreadable] [unreadable] [unreadable]